The present invention relates to a liquid crystal display device having a thin film transistor and, more particularly, to an active matrix type liquid crystal display device using a thin film transistor or the like.
The active matrix type liquid crystal display device is equipped with non-linear elements (or switching elements) respectively corresponding to a plurality of pixel electrodes arrayed in the matrix shape. Since a liquid crystal of each pixel is theoretically driven at all times (at the duty ratio of 1.0), the active type device has a better contrast than the so-called "simple matrix type device" which uses a time sharing drive method, and so this technology is indispensable especially in a color liquid crystal display device. The switching elements are representatively exemplified by thin film transistors (TFT).
Examples of the active matrix type liquid crystal display device using a thin film transistor are disclosed in Japanese Patent Laid-Open No. 309921/1988 and in "12.5 type active matrix color liquid crystal display adopting a redundant construction" on pp. 193 to 210 of Nikkei Electronics, issued on Dec. 15, 1986, by NIKKEI MCGRAW-HILL, for example.